image: © Richard Vignola (CC BY-NC-ND)

Here are two possible cause-effect diagrams of the relations between adding people to a software project and relative progress.

Use the up and down arrows in the nodes in the model to:

  • add some new people
  • change your organization such that less coordination between people is required
  • reduce the training load on old workers

What happens to relative progress? When do you see changes? Do you like all the changes you see?

Above was a simple model of Brooks’s Law, taken from “How Software is Built” [Weinberg, 2014]. This is is an open-loop system; there are no feedback loops. This makes it a somewhat simple (but interesting) dynamic.

There is a great way managers can transform this system into a system that will be raging out of control in no time. Consider this management intervention, also from [Weinberg, 2014]:

You might recognize this as Brooks’s Law:

Adding manpower to a late software project makes it later.

[Brooks, 1995]: The Mythical Man-Month: Essays on Software Engineering

All causal loop diagrams are models and thus they're wrong and useful at the same time. You can remix a model to make it more closely represent your context. Please share your remixed model with the world!


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